Replacing old phputf8 with symfony mbstring polyfill (#55)

* Replacing old phputf8 with symfony mbstring polyfill

* trigger notice for null value for strspn()

Author: Hackwar

composer.json

@@ -7,7 +7,8 @@
     "license": "GPL-2.0-or-later",
     "require": {
         "php": "^8.1.0",
-        "symfony/deprecation-contracts": "^2|^3"
+        "symfony/deprecation-contracts": "^2|^3",
+        "symfony/polyfill-mbstring": "^1.31.0"
     },
     "require-dev": {
         "doctrine/inflector": "^1.2",
@@ -28,24 +29,7 @@
     "autoload": {
         "psr-4": {
             "Joomla\\String\\": "src/"
-        },
-        "files": [
-            "src/phputf8/utf8.php",
-            "src/phputf8/ord.php",
-            "src/phputf8/str_ireplace.php",
-            "src/phputf8/str_pad.php",
-            "src/phputf8/str_split.php",
-            "src/phputf8/strcasecmp.php",
-            "src/phputf8/strcspn.php",
-            "src/phputf8/stristr.php",
-            "src/phputf8/strrev.php",
-            "src/phputf8/strspn.php",
-            "src/phputf8/trim.php",
-            "src/phputf8/ucfirst.php",
-            "src/phputf8/ucwords.php",
-            "src/phputf8/utils/ascii.php",
-            "src/phputf8/utils/validation.php"
-        ]
+        }
     },
     "autoload-dev": {
         "psr-4": {
@@ -56,7 +40,8 @@
     "extra": {
         "branch-alias": {
             "dev-2.0-dev": "2.0-dev",
-            "dev-3.x-dev": "3.0-dev"
+            "dev-3.x-dev": "3.x-dev",
+            "dev-4.x-dev": "4.x-dev"
         }
     }
 }